Interactions in polyvinyil acetat - paper adhesive joint and influence on its adhesion parameters

Adhesives have a wide range of applications in various industries including the printing industry. Water based emulsion adhesives being used in printing industry are most often based on polyvinyl acetate (PVAc) homopolymers, especially in bookbinding for short run book production and caseing in. Polyvinyl acetate emulsion adhesive formulations are affordable, regarded as being nontoxic and easy to handle. Designing durable and quality short run products requires understanding the interactions between used materials in adhesive joint and the basic components of paper and adhesive. In this study, the adhesive parameters of polyvinyl acetate adhesive on five paper samples containing different shares of inorganic fillers (0%, 18.5%, 20.5%, 21% and 30%) have been investigated. Paper samples were investigated in the terms of surface roughness, moisture, ash and CaCO3 content. The moisture content was similar as well as surface roughness of all paper sample, except roughness of paper with 0% of inorganic fillers – filter paper. Ranking based on ash content was same as one based on CaCO3 content. Besides the different paper properties, the varying amount of water (0%, 2.5% and 5%) in adhesive have been studied as well. Polyvinyl acetate adhesive was applied on all samples under the same conditions (23°C and 50% RH) and method. The analysis of the surface free energy (SFE) and its polar and dispersive components of paper and adhesive was performed by contact angle measurements. Based on those measurements, excluding a hydrophilic filter paper again, all other paper samples showed hydrophobic character and small SFE values (under 40 mJ/m2). There was no large impact on SFE of hydrophilic adhesive samples due to added amount of water. According to the obtained results, the interfacial free energy between two phases and mechanical work of the adhesion was calculated.